Call establishment in highly congested network environment

ABSTRACT

A communication device establishes a connection in a congested wireless communications network environment by systematically reducing a probability of attempting to connect to a strongest, but overly-congested, cell. A transceiver of the communications device attempts at least one first Random Access Channel (RACH) procedure with a first cell that is currently designated as a serving cell. A RACH controller of the communications device detects a failure to successfully connect to the first cell via the at least one first RACH procedure, autonomously determines, based at least on a probability value, which is greater than 0% and less than 100%, whether to de-prioritize the first cell for a period of time, and, in response to determining to de-prioritize the first cell, reduces a priority value assigned at the UE to the first cell for cell selection/reselection, and assigns a selected time period during which the priority value remains reduced.

BACKGROUND

1. Technical Field

The present disclosure relates to communication devices, and moreparticularly to selection/reselection of a cell for attempting toconnect in a congested cellular environment.

2. Description of the Related Art

Wireless communications systems are widely deployed to provide varioustypes of communication such as voice, packet data, and so on. Thesesystems may be based on code division multiple access (CDMA), timedivision multiple access (TDMA), frequency division multiple access(FDMA), or other multiple access techniques. Such systems can conform tostandards such as Third-Generation Partnership Project 2 (3GPP2, or“cdma2000”), Third-Generation Partnership (3GPP, or “W-CDMA”), or LongTerm Evolution (LTE). In the design of such communications systems, itis desirable to maximize the capacity, or the number of users the systemcan reliably support, given the available resources.

In a cellular communication system, a geographical region is dividedinto a number of cells served by base stations. The base stations areinterconnected by a fixed network which can communicate data between thebase stations as well as a core network. A mobile station or userequipment is served via a radio communication link from the base stationor node of the cell within which the mobile station is camped on.Communication from a mobile station to a base station is known as theuplink, and communication from a base station to a mobile station isknown as the downlink.

The Random Access Channel (RACH) is a contention-based channel forinitial uplink transmission, i.e., from User Equipment (UE) to a basestation. The RACH can be used for several purposes, such as to accessthe network, to request resources, to carry control information, toadjust the time offset of the uplink, to adjust the transmitted power,and to transmit small amounts of data; however, contention resolution isthe key feature of the random access channel.

Many UEs can attempt to access a same base station simultaneously,leading to collisions. In some instances, too many users attempt toestablish a connection to a same cell or base station using a RACHprocedure or too few network interfaces for the cell or base station areavailable because too many users are already connected to the network.In these instances, the RACH procedures of the UE can fail repeatedly.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of the illustrative embodiments is to be read inconjunction with the accompanying drawings, wherein:

FIG. 1 provides a block diagram representation of an example portablecommunication device that operates within a congested network inaccordance with an embodiment of the present invention;

FIG. 2 provides a diagram representation of data structures forselecting/reselecting a cell in the congested network in accordance withan embodiment of the present invention;

FIG. 3 provides a flow diagram of a method of de-prioritizing selectionor reselection of a cell in a congested network environment inaccordance with an embodiment of the present invention;

FIG. 4 provides a flow diagram of an exemplary method of de-prioritizingreselection of the cell after subsequent Radio Access Channel (RACH)failures in accordance with various embodiments of the presentinvention; and

FIG. 5 provides a flow diagram of another exemplary method ofde-prioritizing selection or reselection of the cell using aprobabilistic calculation in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION

In one embodiment, the present disclosure provides a method ofestablishing a connection in a congested cellular network environment. AUser Equipment (UE) attempts at least one first Random Access Channel(RACH) procedure with a first cell that is currently designated as aserving cell for the UE. The UE detects a failure to successfullyconnect to the first cell via the at least one first RACH procedure. TheUE autonomously determines, based at least on a probability value, whichis greater than 0% and less than 100%, whether to de-prioritize thefirst cell for a period of time. In response to determining tode-prioritize the first cell, the UE reduces a priority value assignedat the UE to the first cell for cell selection/reselection and the UEassigns a randomly selected time period during which the priority valueremains reduced.

In another embodiment, the present disclosure provides a communicationdevice that establishes a connection in a congested cellular networkenvironment. A transceiver of a UE attempts at least one first RACHprocedure with a first cell that is currently designated as a servingcell for the UE. A RACH controller: detects a failure to successfullyconnect to the first cell via the at least one first RACH procedure;autonomously determines, based at least on a probability value, which isgreater than 0% and less than 100%, whether to de-prioritize the firstcell for a period of time; and, in response to determining tode-prioritize the first cell, reduces a priority value assigned at theUE to the first cell for cell selection/reselection, and assigns arandomly selected time period during which the priority value remainsreduced.

The above as well as additional features and advantages of the presentinnovation will become apparent in the following detailed writtendescription of a method and a communication device. De-prioritization isemployed in selecting/reselecting a best cell in a highly congestedenvironment such that only a subset of similarly situated UsersEquipment (UEs) are likely to attempt a RACH procedure to a weaker cell.In particular, a load on a highly congested cell can be reduced bymoving, for randomly selected de-prioritization periods, a random set ofsuch UEs that experience one or more different RACH failures orrejections from the network due to a congested cell or Radio AccessTechnology (RAT). Thereby, a better possibility of a successful call isprovided to the UE and a reduction in peak RACH congestion is realizedby the highly congested cell.

In the following detailed description of exemplary embodiments of theinnovation, specific exemplary embodiments in which the innovation maybe practiced are described in sufficient detail to enable those skilledin the art to practice the innovation, and it is to be understood thatother embodiments may be utilized and that logical, architectural,programmatic, mechanical, electrical and other changes may be madewithout departing from the spirit or scope of the present innovation.The following detailed description is, therefore, not to be taken in alimiting sense, and the scope of the present innovation is defined bythe appended claims and equivalents thereof.

Within the descriptions of the figures, similar elements are providedsimilar names and reference numerals as those of the previous figure(s).Where a later figure utilizes the element in a different context or withdifferent functionality, the element is provided a different leadingnumeral representative of the figure number. The specific numeralsassigned to the elements are provided solely to aid in the descriptionand not meant to imply any limitations (structural or functional orotherwise) on the described embodiment.

It is understood that the use of specific component, device and/orparameter names (such as those of the executing utility/logic describedherein) are for example only and not meant to imply any limitations onthe described embodiments. The presented embodiments may thus beimplemented with different nomenclature/terminology utilized to describethe components, or devices or parameters herein, without limitation.Each term utilized herein is to be given its broadest interpretationgiven the context in which that terms is utilized.

As further described below, implementation of the functional features ofthe innovation is provided within processing devices/structures andinvolves use of a combination of hardware, firmware, as well as severalsoftware-level constructs (e.g., program code). The presented figuresillustrate both hardware components and software components withinexample data processing.

With reference now to the figures, FIG. 1 is a block diagram of awireless communication system in accordance with an embodiment of thepresent invention. The communication system includes one or morewireless communication devices 100, such as but not limited to acellular telephone, a radio telephone, a smartphone, or a personaldigital assistant (PDA), a laptop computer, personal computer, or tabletcomputer with radio frequency (RF) capabilities, in communication with awireless communications network 138. In various technologies, wirelesscommunication device 100 may be referred to as a user equipment (UE), amobile station (MS), a subscriber station (SS), a subscriber unit (SU),an access terminal (AT), and so on and, for ease of reference, is alsoreferred to herein as a UE. As illustrated by FIG. 1, UE 100 comprises aprocessor 102, such as one or more microprocessors, microcontrollers,digital signal processors (DSPs), combinations thereof or such otherdevices known to those having ordinary skill in the art. The particularoperations/functions of processor 102, and thus of UE 100, is determinedby an execution of software instructions and routines that are stored ina respective at least one memory device 104 associated with theprocessor, such as random access memory (RAM), dynamic random accessmemory (DRAM), and/or read only memory (ROM) or equivalents thereof,that store data and programs that may be executed by the correspondingprocessor. The processor 102 controls the communication and otherfunctions and/or operations of communication device 100. These functionsand/or operations include, but are not limited to, data processing andsignal processing.

In this example, the UE 100 may be implemented with a bus architecture,represented generally by a bus 109. The bus 109 may include any numberof interconnecting buses and bridges depending on the specificapplication of the UE 100 and the overall design constraints. The bus109 links together various circuits including one or more processors,represented generally by the processor IC 102, and readable storagemedia, represented generally by at least one memory device 104. A businterface 110 provides an interface between the bus 109 and atransceiver 111. The transceiver 111 provides a means for communicatingwith various other apparatuses over a transmission medium. In theexemplary embodiment, the transceiver 111 performs Radio Frequency (RF)cellular communication via one or more antennas 112.

Processor 102 is coupled to a power management circuit 116, whichcontrols the allocation of electrical power to the various components ofUE 100. Processor 102 receives electrical power via power managementcircuit 116, which couples to a power source, such as a battery or acharging circuit (not shown). Power management circuit 116 also provideselectrical power to the various input, output and functional devices,described below, as well as other on-board integrated circuits 117.

UE 100 also comprises input devices, of which keypad 118, touch screen(or touch pad) 119 and microphone 120 are illustrated, connected toprocessor 102. Additionally, UE 100 comprises output devices, which areeach connected to processor 102. Specifically, UE 100 in FIG. 1comprises speaker 121 and display 122.

In addition to the transceiver 111, UE 100 may also include othercomponents utilized to enable other forms of communication. Forinstance, several other data communication components may be providedwithin wireless communication devices such as UE 100 to enable apersonal access network (PAN) or other capabilities. Among thesecomponents may be an infrared (IR) transceiver 128, a Bluetoothtransceiver 130, a Wireless Local Access Network (WLAN) transceiver 132,and a wired communication module 134, which may be a universal serialbus (USB) connector that links UE 100 to another device via a USB orother serial cable.

The processor 102 is responsible for managing the bus 109 and generalprocessing, including the execution of software stored on the memory104. The software, when executed by the processor 102, causes UE 100 toperform various functions, some of which are described herein. The atleast one memory device 104 may also be used for storing data that ismanipulated by the processor 102 when executing software. In anexemplary embodiment, a RACH controller 113 in at least one memorydevice 104 selects or reselects a Radio Access Network (RAN) or RadioAccess Technology (RAT) with reference to tracking data maintained in acell select/reselect table 114 that is resident in at least one memorydevice 104. For instance, the RACH controller 113 can implementde-prioritization techniques in order to achieve a timely connection viathe transceiver 111, on one or more service(s) supported by UE 100. Sucha service can be performed for an application 115 that resides in atleast one memory device 104 and is executed by processor 102.Alternatively to being wholly in memory 104, the RACH controller 113 canhave a distributed design, such as being at least in part implemented infirmware or other dedicated circuitry (e.g., modules).

According to one embodiment, the UE 100 receives motion, proximity,triangulation, or geospatial coordinates data via one of thecommunication components of the UE or from a dedicated location sensor135. From this data, UE 100 can determine whether the UE is stationaryor moving, and thus whether a subsequent RACH procedure can continue tobe directed to a congested cell. Alternatively or in addition, the datacan indicate whether UE 100 is relatively stationary with regard to thecurrent serving cell or best cell. For instance, UE 100 can be in publictransportation conveyance with a femtocell that provides a cell forcellular communication. As another example, the UE 100 can be moving atpedestrian speeds and thus be relatively stationary.

Communication device 100 can comprise subscriber identification 136 foraccessing one or more types of Radio Access Networks (RANs) or CoreNetworks. For example, UE 100 may be a global system for mobilecommunication (GSM) mobile phone and thus includes a Subscriber IdentityModule (SIM) card that connects to processor 102 via a SIM adapter/port(not shown). The SIM card may be utilized as a storage device forstoring data and the subscriber identification 136. Alternatively or inaddition, the subscriber identification 136 may support othercommunication protocols or hardware architectures by including a virtualSIM, Removable User Identification Module (RUIM), Universal IntegratedCircuit Card (UICC), etc. The subscriber identification 136 may also bestored within memory 104.

In addition to the above hardware components, several functions of UE100 and specific features of the described embodiments may be providedas functional code and/or utility that is stored within memory 104 andexecuted by data processor 106 on processor 102. In one or moreembodiments, the processor can execute various functional code (orfirmware), such as RACH controller 113 by which UE 100 attempts toconnect to cellular network 138, which for clarity is depicted as acombination of multiple cells 142, 144 (two shown) coupled to a corenetwork 140.

FIG. 1 also illustrates two adjacent cells, a first cell 142 and asecond cell 144, each of which is provided wireless service by arespective base station 146, 148 and each of which is in communicationreach of UE 100. Until such time as a connection is required, UE 100 cancamp on a best cell, such as the first cell 142, which then functions asa serving cell for the UE.

Periodically, a UE, such as UE 100, can perform an acquisition scan todetermine what neighboring cells are of sufficient strength to befrequently monitored. The UE periodically monitors certain downlinkchannels of neighboring cells in order to determine signal strength ofeach cell for prioritizing a “best cell,” a second best cell, and so on.The UE can also receive certain broadcast information and measurecertain frequency and time offsets, etc., in order to expedite a handoffif necessary. The UE camps on the serving cell when not engaged in anactive connection, periodically receiving pages from the serving celland periodically making reports. While in this mode, the UE can conservepower by using discontinuous transmission and discontinuous reception.The UE can be entering service (e.g., moving from an area not served bya cell or powering up) and determining a best cell that is not yet aserving cell.

When a UE, such as UE 100, desires to attempt a connection with a basestation of a serving cell, such as the base station 146 of the servingcell 142, in order to reach the cellular network 138, the UE can performa Random Access Channel (RACH) procedure 150 on a first RACH 152 of theserving cell. RACH procedure 150 is used in mobile phones or otherwireless devices, such as UE 100, when the wireless communication deviceneeds to get the attention of a base station (e.g., base station 146) inorder to initially synchronize transmission of the UE 100 with the basestation. It should be appreciated with the benefit of the presentdisclosure that RACH procedure 150 can generally refer to acontention-based uplink channel.

In various instances, UE 100 may fail to reach the base station 146 byRACH procedure 150. For instance, other users' equipment (UEs), such asUEs 156, can contend via the RACH procedure for the attention of thebase station 146. In particular, UE 100 and the other UEs 156 can bestationary for an extended period of time within a crowded location orvenue 154 (e.g., a crowded sports stadium, a concert, etc.) being servedprimarily by the first cell 142.

In an exemplary embodiment, the transceiver 111 of UE 100, via RACHcontroller 113, attempts at least one first RACH procedure 150 with thefirst cell 142 that is currently serving as the serving cell for UE.RACH controller 113 detects a failure to successfully connect to thefirst cell 142 via the at least one first RACH procedure 150. Responsiveto the failure, the RACH controller 113 autonomously determines, basedat least on a probability value, whether to de-prioritize the first cell142 for a period of time. In the described embodiments, the probabilityvalue is greater than 0% and less than 100%. In response to the RACHcontroller 113 determining to de-prioritize the first cell 142, the RACHcontroller 113 reduces a priority value assigned at UE 100 to the firstcell 142 for cell selection/reselection, and the RACH controller 113assigns a randomly selected time period during which the priority valueremains reduced. De-prioritization of the first cell 142 results in ahigher probability of selection of the second cell 144 for a subsequentRACH procedure 160 on a second RACH 162 of the second cell 144. Aspectsof this de-prioritization scheme involve use of a cellselection/reselection table, which is illustrated by FIG. 2 anddescribed hereafter.

As used herein, a “cellular network” is a system that includes one ormore network-based communication devices that communicate with wirelessuser communication devices in the system and that manage communicationbetween the communication devices. Cellular network 138 is depicted in ageneralized manner. For example, cellular network 138 includes multiplebase stations (BSs) 146, 148, such as but not limited to a Base Node(Node B), an evolved Base Node (eNB), an Access Point, or a BaseTransceiver Station (BTS). Each base station (BS) 146, 148 provideswireless service to the UEs residing in a corresponding coverage area(e.g., cells 142, 144) of the BS 146, 148 via a corresponding airinterface.

The above introduced cellular network 138 may be any type ofcommunication system that implements voice or data communicationservices. For example, cellular network 138 may operate according to,but not limited to, any one or more of the OMA (Open Mobile Alliance),3GPP (3rd Generation Partnership Project), 3GPP2 (3rd GenerationPartnership Project 2), IEEE (Institute of Electrical and ElectronicsEngineers) 802.xx, European Telecommunications Standards Institute(ETSI), and WiMAX Forum standards.

The air interfaces can operate in accordance with the particular accesstechnology supported by the corresponding BS. For example, the airinterfaces may all utilize a same technology or they may utilizedifferent access technologies. Moreover, each UE includes the capabilityto communicate with a BS through one or more wireless communicationprotocols such as Advanced Mobile Phone System (AMPS), Code divisionmultiple access (CDMA), Time division multiple access (TDMA), GlobalSystem for Mobile communications (GSM), Integrated Digital EnhancedNetwork (IDEN), General Packet Radio Service (GPRS), Enhanced Data ratesfor GSM Evolution (EDGE), Universal Mobile Telecommunications System(UMTS), Wideband Code Division Multiple Access (WCDMA), Code divisionmultiple access 6000 (CDMA6000), Long term evolution (LTE), evolved UMTSTerrestrial Radio Access Network (EUTRAN), and their variants.

Referring now to FIG. 2, an example data structure 200 is depicted thatprovides data for the RACH controller 113 to utilize as well asproviding a means of tracking prior actions by the RACH controller 113.A de-prioritization and selection/reselection (DSR) table 202 ispopulated with node or cell identification (“A, B, C”) for those cellsdetected as having sufficient strength for continued monitoring. The UEhas an amount of time for tuning away from a serving cell in order toperform measurements of the neighboring cell with time resourcesgenerally prioritized by the relative strength of the cells. Thismonitoring expedites selection or reselection when the UE is inactive(i.e., no current connection for voice or data services) or facilitatesa handoff when the UE is moving between cells. Determining which cell isthe best or second best for connecting to and enabling the UE to performa particular voice or data service can be based at least in part upondetected signal strength. For clarity, values are inserted in the DSRtable 202 that are not scaled or given units of measure for anyparticular technology or protocol. In this instance, the signal strengthis mapped to a default select/reselect priority value. When a congestednetwork is not detected, then selection or reselection is performed asconventionally understood and de-prioritization of a cell's assignedpriority value is not appropriate.

De-prioritization selection/reselection table 202 includes records withthe following fields or columns. A node/cell identifier field identifiesa node or cell. For example, and for the purpose of illustrating theprinciples of the present invention, three cells are indicated withinthe example table, namely cells A, B, and C. A signal strength fieldcontains measured signal strength or other similar value for each cell.A select/reselect priority field provides a priority that initiallydefaults to a value correlated to the signal strength of a cell or otherassociated and/or similar cell characteristics that are indicative ofwhich cell should be selected for initiating a next connection request.A de-prioritized priority value field can be used to temporarily hold asubstitute priority value for the select/reselect priority field whende-prioritization of the cell occurs and/or remains in effect. A numberof RACH failures field is utilized to track a number of successive RACHfailures for a particular node/cell. The tracking can be as a functionof time, for example, since a last power up, since entering a particularnode/cell, etc. A service requested field can indicate which one of aplurality of services can be offered by a particular node/cell orrequested by the UE, so that congestion can be evaluated and resultingde-prioritization can be performed granularly on a per-service-basiswithin a single cell. A probability to de-prioritize field can berandomly or deterministically populated with a probability value that isused by a de-prioritization algorithm to weight the likelihood ofde-prioritizing a cell prior to a subsequent RACH procedure. Byutilizing the probability value within the algorithm, a likelihood isreduced that a group of UEs that are confronted with a same congestedcell will all switch to a weaker node or cell at the same time. It isappreciated that absent this safeguard, as well as an additionalsafeguard related to random selection of a de-prioritized timer value,an automatic de-prioritization process may create a secondary problem ofoverwhelming a secondary cell.

In one embodiment, one or more congested conditions can be detected orreceived and reported as a pre-condition to performingde-prioritization. These detected or received congested conditions canalso be used to affect a priority or a probability value. In anexemplary embodiment, three fields associated with congested conditionindicators are depicted within data structure 200, namely a ‘NetworkBroadcast’ field, a ‘Network Rejection of RACH procedure’ field, and a‘Downlink Traffic’ field. An additional enabling condition forde-prioritization is depicted as a ‘Location’ field, which indicates orcan be processed to determine whether the UE is stationary, orrelatively stationary. In one implementation of the describedembodiments, the RACH controller 113 does not de-prioritize a cell'spriority value unless the UE is relatively stationary within the celllocation. Thus, a UE that is not stationary relative to the cells willnot experience a de-prioritization due to a failed RACH. Ade-prioritized field flags, that is, indicates, whether the base stationor cell, or the base station or cell on a per service basis, is beingde-prioritized. A de-prioritization timer value field can indicate whatrandomly selected time period was used for the de-prioritization. A timeremaining field can indicate what portion of the de-prioritization timeperiod remains. It is appreciated that the above fields are merelyprovided for illustration and are simply exemplary types of fields thatcan be included in such a data structure. Additional fields, lessfields, and/or different types of fields can be utilized in any oneimplementation of the described embodiments. Also the data may be storedin different locations rather than being present within a single datastructure 200.

The following description refers to the functional implementation and/orusage of the data structure during device operation in a three cellenvironment, with the serving cell identified as cell A (for example,cell 142). At time T1 as depicted at 204, a RACH procedure to obtain afirst service, that is, Service 1, via cell A has failed. The failureitself can be used as an indication of a congested network.Alternatively or in addition, a congested condition may be detected. Inthis instance, neither network broadcast (“NW bcast”) nor an explicitnetwork rejection to the UE has confirmed a congested network for cellA. However, the UE has monitored downlink traffic and determined thatthe number of connections as a function of time is greater than athreshold, indicating network congestion.

In response to the RACH failure and/or the de-prioritization condition,the RACH controller 113 accesses a de-prioritization probability lookuptable 206. By reference to the table, the RACH controller 113 determinesa probability of de-prioritizing cell or reducing cell priority as afunction of a number of connection setup failures. Using thisprobability, the RACH controller 113 determines that, in this instance,the next selection/reselection would be to the same cell, and thede-prioritized priority is indicated as “deferred.” However, it isapparent that, using the probability, it is possible that the RACHcontroller 113 could have determined to de-prioritize at this firstinstance of a failure. It should be appreciated with the benefit of thepresent disclosure that a higher probability value corresponds to ahigher likelihood of de-prioritization. For instance, a first failuremapped to a 55% probability is less likely to result inde-prioritization than the 6^(th) failure at 80% probability.

At a second time T2 as depicted at 208, the RACH controller 113 hastracked four failed RACH procedures to cell A and retrieves, from table206, a probability of de-prioritizing of 70%, corresponding to four (4)RACH failures. The 70% probability is reflected within DSR table 202.RACH controller 113 executes the algorithm that randomly determines,correlated to the probability value, whether to de-prioritize thepriority value (70) of the serving cell A. As indicated by the DSR tableat T2 208, RACH controller 113 de-prioritizes the priority value ofserving cell A from 70 to 50 after four (4) RACH failures. In analternative embodiment, the de-prioritized priority value of the cellcould be set to a very low value (e.g., 0) so that a de-prioritized cellwill only be chosen as the serving cell if there are no other cellsremaining that have not undergone de-prioritization. During subsequentRACH procedures, RACH controller 113 temporarily substitutes thede-prioritized value of 50 for cell A in determining which cell toselect to complete the subsequent RACH. The de-prioritized value istemporarily substituted for the signal strength-based priority of 70 asshown, for instance. The RACH controller 113 also randomly selects atime for de-prioritizing the cell, that is, cell A, by selecting fromwithin a de-prioritization timer period lookup table 210. In oneembodiment, certain factors are utilized to shorten or lengthen the timebefore restoring the priority value of the de-prioritized cell, cell A,to its original value. For instance, the time period can be a randomfunction 212 of selecting one time value of different time valuesbetween 10 seconds and 60 seconds. Alternatively, in another embodiment,the time value can be defined in terms of multiples of a period of timesufficient for a UE to complete one RACH procedure. Also at time T2 208,the RACH controller 113 selects a second best cell, that is, cell B (forexample, cell 144), to connect to via the next or subsequent RACHprocedure, as cell B now has a higher priority value of 60 than cell A'sde-prioritized priority value of 50.

At a third time T3 as depicted at 214, the RACH controller 113 hasdetected one or more RACH procedure failures on the second cell, cell B,and has de-prioritized the second cell B after the first RACH failure.However, the second cell B still has a higher cell selection priorityvalue, that is, 55, than the priority value of cell A, which remains at50 until the time remaining field reduces to zero (0). As shown, thetime remaining for removal of the de-prioritization status of cell A is0.2 units of the original 1.8 units of time assigned. Thus, the nextRACH request will again be handled by cell B. Notably, the presence ofsome time remaining, 0.5 units, for cell B does not affect thesubsequent RACH request being handled by cell B since cell B stillremains the higher priority cell for reselection.

As further illustrated at time T3, de-prioritization can be determinedbased on what service is being sought. A cell can provide certain voiceand data and/or multimedia services that can experience congestion on aservice-by-service basis. Such services can also be distinct based uponwhat Radio Access Technology (RAT) is required to use the service. TheUE can choose to de-prioritize a best cell or a serving cell only forsubsequent connection requests for the same first service (Service 1)based on RACH procedure failures and/or detected congested conditionsaffecting the first service. The UE can select or reselect the same bestcell or serving cell for another second service (Service 2), regardlessof the de-prioritization status of the best cell relative to the firstservice.

In an exemplary embodiment, UE 100 determines that the failure tosuccessfully connect during the first RACH procedure was for initiatinga first service, requested by the UE, of a plurality of differentservices that are supported by the first cell, including at least onedifferent second service. As a specific example, the first service maybe a voice service while the second service may be an SMS text service.UE 100 de-prioritizes the first cell with respect to completion of thefirst service, that is, the voice communication service. An identifierof the first cell is tagged with the first de-prioritized priorityvalue, which causes the UE to initiate the at least one subsequent RACHprocedure for the first service via a suitable second cell if oneexists. The RACH procedure for the second service then can be completedvia the first cell, regardless of the fact that the first cell has beende-prioritized relative to completion of a RACH for the first service.When the UE issues a subsequent RACH procedure for completion of the atleast one different, second service via the first cell, each service ofthe plurality of different services, e.g., Services 1 and 2 at time T3,are individually assigned the first priority value as a defaultassignment of the serving cell and each different service thatexperiences a de-prioritizing condition associated with that specificservice is subsequently assigned an individual de-prioritizing value fora selected time period in response to an occurrence of thede-prioritizing condition associated with that specific service.

Referring now to FIG. 3, there is presented a flow diagram 300illustrating a method by which a UE, such as UE 100, operates toestablish a connection in a congested cellular network environment inaccordance with an embodiment of the present invention. The UE attemptsat least one first Random Access Channel (RACH) procedure with a firstcell, such as cell 142, that is currently designated as a serving cellfor the UE (block 302). The UE detects a failure to successfully connectto the first cell via the at least one first RACH procedure (block 304).The UE autonomously determines, based at least on a probability value,which is greater than 0% and less than 100%, whether to de-prioritizethe first cell for a period of time (block 306).

In one embodiment, the UE assigns a randomly selected time period fromamong a range of available time periods, wherein the range of availabletime periods comprises at least a first, shorter time period duringwhich at least one subsequent RACH procedure can be completed by the UEand a second, longer time period during which multiple subsequent RACHprocedures can be completed by the UE (block 308). In response todetermining to de-prioritize the first cell, the UE reduces a priorityvalue assigned at the UE to the first cell for cellselection/reselection, and assigns a selected time period during whichthe priority value remains reduced (block 310).

Referring now to FIG. 4, flow diagram 400 is provided illustratingvarious exemplary embodiments by which a UE, such as UE 100, may furtherbalance efficient connection in a congested network environment overrepeated RACH attempts. The UE experiences at least one first RACHfailure with a first cell (block 401), such as cell 142, and attempts atleast one subsequent RACH procedure with the first cell (block 402). Inone implementation, the subsequent RACH procedure can be attempted witha second cell, such as cell 144, if the UE, and in particular a RACHcontroller of the UE, such as the RACH controller 113 of UE 100, electsto de-prioritize the first cell after the at least one first RACHfailure. A determination is made whether the subsequent RACH procedurefails at the first cell (block 404).

If no failure is detected (and in one alternative embodiment no otherde-prioritization condition is present), the UE continues to operatewith the first cell as the serving cell. The RACH controller maintainsthe default priority value of the first cell (block 405). Also, if theprobability value had been previously increased as a result of failureof the at least one first RACH procedure, the RACH controller restoresthe probability to a default low probability value. Similarly, if theprobability value was previously increased due to the presence of aprevious de-prioritizing condition, then the probability value isrestored to a low probability value, approaching zero (0) probability(block 405). It should be noted as well that, in response to expirationof a time period following de-prioritizing of the first cell, the UErestores the priority value to a default priority value for the firstcell and the UE automatically resets the probability value to a baselinelow probability.

In a particular embodiment for the incremental probability adjustmentsdescribed herein, in response to the failure of the subsequent RACHprocedure, the UE tracks a number of failures to successfully connect tothe first cell via the at least one first RACH procedure and eachsubsequent RACH procedure (block 406).

In one embodiment, the UE can evaluate one or more de-prioritizationenabling conditions, including and/or in addition to the RACH failure(alternate block 408). In the exemplary embodiment of FIG. 4, a firstde-prioritization enabling condition is depicted as location information410, which indicates whether the UE is stationary (block 412). A secondde-prioritization enabling condition is depicted as a broadcast message414 that indicates whether the first cell is congested (block 416). Athird de-prioritization enabling condition is depicted as a rejectionmessage 418 from the network that indicates whether the first cell iscongested (block 420). A fourth de-prioritization enabling condition isdepicted as a monitored downlink 422 from the network that can be usedto determine a number of connection setups over a period of time andwhether the number exceed a threshold (block 424). It is howeverappreciated that in most embodiments, the tracked RACH failures canprovide a sole basis for inferring network congestion. In one suchde-prioritization conditions evaluation embodiment, the UE, at block404, may performs the de-prioritization of the first cell only if atleast one of a group of conditions is detected (see D-P Condition inblock 404). The group of conditions comprises (a) a previously receivedbroadcast message indicates that a congested cell condition exists, (b)the network responds to a request by the UE for a connection with areject message containing a cause value which indicates that a congestedcell condition exists, (c) a monitoring of the downlink channelsindicates that the number of connection setups being performed by thenetwork per unit time has exceeded a threshold, and (d) a monitoring ofthe downlink channels indicates that the network is transmitting toother UEs a reject message containing a cause value which indicates thata congested cell condition exists, wherein the number of such rejectmessages being transmitted to other UEs has exceeded a threshold.

In another such de-prioritization conditions evaluation embodiment, theUE may detect that the UE is in motion relative to a location at whichthe priority of the first cell could have been de-prioritized. The UEautomatically resets the priority value of the first cell to a defaultpriority value in response to detecting that the UE is in motion andthat the priority value of the first cell is currently a de-prioritizedvalue.

In various other embodiments of the present invention, satisfying one ormore conditions can be required to begin de-prioritization.Alternatively or in addition, satisfying one or more conditions can alsobe required to continue a previously implemented de-prioritization.Alternatively or in addition, one or more conditions can affect aprobability of de-prioritization. In the illustrative depiction, bothuses of de-prioritization conditions are shown, both in determiningwhether to de-prioritize and in adjusting a probability for selection orreselection during de-prioritization.

Basing a probability of de-prioritization first on a number of failuresprovides an inference that congestion exists. Then the probability canbe upwardly adjusted when a condition is detected that corroborates orconfirms the congestion. The group of conditions comprises (a) apreviously received broadcast message indicates that a congested cellcondition exists, (b) the network responds to a request by the UE for aconnection with a reject message containing a cause value whichindicates that a congested cell condition exists, (c) a monitoring ofthe downlink channels indicates that the number of connection setupsbeing performed by the network per unit time has exceeded a threshold,and (d) a monitoring of the downlink channels indicates that the networkis transmitting to other UEs a reject message containing a cause valuewhich indicates that a congested cell condition exists, and the numberof such reject messages being transmitted to other UEs has exceeded athreshold. In one embodiment, the UE increases the probability value forde-prioritizing the first cell by increasing the probability valuebetween more than 0% and less than 100%, with the increases directlyco-related to a number of consecutive failures registered forconsecutive RACH procedures. A higher probability value makes it morelikely that the UE will de-prioritize the priority value of the firstcell.

In one such embodiment, based upon the tracking of the failures (block406), the UE increases the probability value for de-prioritizing thefirst cell in response to detecting that at least one failure hasoccurred during subsequent RACH procedures on the first cell. Forinstance, the UE can increase the probability value for de-prioritizingthe first cell for each consecutive failure detected as previouslydescribed in FIG. 2, wherein the probability value increases from abaseline low probability to a high probability in ‘N’ number ofincrements based on the number of RACH failures (block 426).

Alternatively or in addition to adjusting probability based on thenumber of failures, the UE can adjust the probability value forde-prioritizing the first cell as a function of whether one or more of agroup of other de-prioritizing conditions is detected (block 428). Basedupon the current probability value, the UE probabilistically determinesto reduce the priority value utilized to select or reselect the cell forfuture connection requests (block 430).

The UE determines whether a second cell has a higher priority than thede-prioritized first cell (block 432). If not, the UE attempts asubsequent RACH procedure with the first cell (block 402). In yet ananother embodiment, the UE reduces the priority value assigned at the UEto the first cell for cell selection/reselection to ensure that the UEdoes not select the first cell during a subsequent RACH procedure whenat least one suitable second cell is also present with a defaultpriority. If one suitable second cell exists with a higher priority,then the UE selects the second cell (block 434). The UE then performsthe subsequent RACH procedure with the second cell and the UE appliesthe same de-prioritization algorithm for failures to connect to thesecond cell as described above for the first cell (block 436).

In still another embodiment, in response to de-prioritizing the firstcell, the UE initiates a subsequent RACH procedure, during a period oftime before expiration of the selected time, to one or more selectedsecond cells. As described herein, the second cells are selected basedin part on the priority value of the particular cell relative to thede-prioritized value of the first cell.

In a particular embodiment, the UE attempts at least one subsequent RACHprocedure with the at least one suitable second cell. In response todetecting a failure to successfully connect to the at least one suitablesecond cell via the at least one subsequent RACH procedure, the UEautonomously determines, based at least on a second probability value,which is greater than 0% and less than 100%, whether to de-prioritizethe at least one suitable second cell for a second time period. Inresponse to determining to de-prioritize the at least one suitablesecond cell, UE reduces a second priority value assigned at the UE tothe at least one suitable second cell for cell selection/reselection,and the UE assigns a randomly selected second time period during whichthe second priority value remains reduced.

Referring now to FIG. 5, a flow diagram 500 is provided that illustratesa method by which a UE, such as UE 100, may establish a connection in acongested cellular network environment in accordance with still otherembodiments of the present invention. The flow diagram 500 begins withpower being provided to the UE (block 502). The UE sets a counter to 0(block 504). The UE determines whether a service request is detected(block 506). If a service request is detected, then the UE starts theRACH procedure (block 508). The UE then determines whether the RACHprocedure is successful (block 510). If the RACH procedure issuccessful, the UE sets the counter to zero (block 512) and the flowdiagram 500 ends. However, if the RACH procedure is unsuccessful, inblock 510, then the UE selects a first random number from a set of {0,1}(block 514). The UE determines whether the first random number, RND1, is‘0’ (block 516). If RND1 equals ‘0,’ the UE sets the counter equal to(counter+1)MOD 10 (block 518). The UE then selects a second randomnumber, RND2, from a set {0 . . . 9} (block 520). Then the UE determineswhether the counter is less than the second random number (block 522).If the counter is not less than RND2, or if the first random number wasdetermined to be one (1) in block 516, then the UE de-prioritizes aserving cell, such as cell 142 (block 524) and performsselection/reselection to a higher priority cell, such as cell 144, if ahigher priority cell is available (block 526).

The UE then may determine whether continued de-prioritization iswarranted based upon the continuation of one or more de-prioritizationconditions. Specifically the UE determines whether a de-prioritizationcondition continues to exist for a currently de-prioritized cell, suchas de-prioritized cell 142 (block 528). In the illustrative embodiment,continued de-prioritization is warranted when one of a plurality ofde-prioritization conditions continues to exist following the initialde-prioritization. Among these continuing de-prioritization conditionsare: (a) the timer has not yet expired, (b) the UE is not currentlymobile, and/or (c) a desired service/core network is unchanged from aprevious attempt. An occurrence of an expired timer, a detected movementof the UE, and/or a change in the desired service network, may trigger areset of the UE parameters, including at least the priority value andthe probability value. Thus, a determination is made as to whether anyof the applicable de-prioritization condition(s) remain (block 530). Ifnone of the conditions remain, the UE restores, for the de-prioritizedcell, an original priority for selection or reselection of the cell(block 532), and the method moves to block 534 at which the UE performsreselection to the highest priority cell available. The reselection tothe highest priority cell available is performed by the UE only if thecell on which the UE is currently camped is not the highest prioritycell available. However, if the de-prioritization conditions associatedwith the de-prioritized cell continue to persist, as determined at block530, then the UE performs a next RACH and subsequent RACHs utilizingreselection based on the highest priority cell that is available (block534). Returning to block 522, if the counter is not less than the secondrandom number, then no de-prioritization of the current serving cell istriggered and the method proceeds to block 534.

By virtue of the foregoing, it should be appreciated that adjusting aprobability of selecting or reselecting a cell for a RACH procedureultimately mitigates the congestion due to too numerous RACH attemptswithin a single cell on a network. Also, by staggering and/orrandomizing the process for determining when to de-prioritize a servingcell following one or more RACH failures, a mechanism is provided bywhich multiple UEs within a same serving cell may each attempt toconnect via a second cell at a different time, thus increasing thelikelihood that the UEs will eventually connect via either the firstcell or the second cell, without all of the UEs collectively,automatically, migrating to the second cell following a single RACHfailure.

The previously-described embodiments can provide a trade-off among anamount of time required for a UE to connect, a congestion on particularcell, and an interference to the network. In de-prioritizing a cell,typically the second cell selected will be at a greater distance orotherwise be subject to greater channel fading. Thus, the UE and thesecond cell may be required to transmit at a greater transmit power inorder to successfully complete the RACH procedure. Thus, greaterinterference might be experienced by the first cell and other UEs. Byintroducing a probability of de-prioritizing and other optimizations,the number of UEs that select one or more second cells can be balancedagainst an amount of network interference that might result from such aselection. Thereby, a secondary problem is avoided or mitigated whereinan increased transmit power necessary to reach the weaker cell createsinterference to other UEs and the best cell.

In each of the flow charts above, one or more of the methods may beembodied in a computer readable storage medium containing computerreadable code such that a series of steps are performed when thecomputer readable code is executed on a computing device. In someimplementations, certain steps of the methods are combined, performedsimultaneously or in a different order, or perhaps omitted, withoutdeviating from the spirit and scope of the innovation. Thus, while themethod steps are described and illustrated in a particular sequence, useof a specific sequence of steps is not meant to imply any limitations onthe innovation. Changes may be made with regards to the sequence ofsteps without departing from the spirit or scope of the presentinnovation. Use of a particular sequence is therefore, not to be takenin a limiting sense, and the scope of the present innovation is definedonly by the appended claims.

As will be appreciated by one skilled in the art, embodiments of thepresent innovation may be embodied as a system, method or computerprogram product. Accordingly, embodiments of the present innovation maytake the form of an entirely hardware embodiment, an entirely softwareembodiment (including firmware, resident software, micro-code, etc.) oran embodiment combining software and hardware embodiments that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, embodiments of the present innovation may take the form ofa computer program product embodied in one or more computer readablestorage medium(s) having computer readable program code embodiedthereon.

Program code embodied on a computer readable storage medium may betransmitted using any appropriate medium, including but not limited towireless, wireline, optical fiber cable, R.F, etc., or any suitablecombination of the foregoing. Computer program code for carrying outoperations for embodiments of the present innovation may be written inany combination of one or more programming languages, including anobject oriented programming language such as Java, Smalltalk, C++ or thelike and conventional procedural programming languages, such as the “C”programming language or assembly level programming or similarprogramming languages.

Aspects of the present innovation are described above with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinnovation. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable storage medium that can direct a computer, other programmabledata processing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablestorage medium produce an article of manufacture including instructionswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks. The computer program instructions may also beloaded onto a computer, other programmable data processing apparatus, orother devices to cause a series of operational steps to be performed onthe computer, other programmable apparatus or other devices to produce acomputer implemented process such that the instructions which execute onthe computer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

While the innovation has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the innovation. Inaddition, many modifications may be made to adapt a particular system,device or component thereof to the teachings of the innovation withoutdeparting from the essential scope thereof Therefore, it is intendedthat the innovation not be limited to the particular embodimentsdisclosed for carrying out this innovation, but that the innovation willinclude all embodiments falling within the scope of the appended claims.Moreover, the use of the terms first, second, etc. do not denote anyorder or importance, but rather the terms first, second, etc. are usedto distinguish one element from another.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the innovation.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present innovation has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the innovation in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the innovation. Theembodiment was chosen and described in order to best explain theprinciples of the innovation and the practical application, and toenable others of ordinary skill in the art to understand the innovationfor various embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. A method of establishing a connection in acongested wireless communications network environment, the methodcomprising: attempting, by a user equipment (UE), at least one firstRandom Access Channel (RACH) procedure with a first cell that iscurrently designated as a serving cell for the UE; detecting a failureto successfully connect to the first cell via the at least one firstRACH procedure; autonomously determining, based at least on aprobability value, which is greater than 0% and less than 100%, whetherto de-prioritize the first cell for a period of time; and in response todetermining to de-prioritize the first cell, reducing a priority valueassigned at the UE to the first cell for cell selection/reselection, andassigning a selected time period during which the priority value remainsreduced.
 2. The method of claim 1, wherein in response to detecting thatat least one failure has occurred during subsequent RACH procedures onthe first cell, increasing the probability value for de-prioritizing thefirst cell.
 3. The method of claim 2, wherein the increasing of theprobability value for de-prioritizing the first cell is only performedif at least one of a group of conditions is detected, the group ofconditions comprising: a previously received broadcast message indicatesthat a congested cell condition exists; the wireless communicationsnetwork responds to a request by the UE for a connection with a rejectmessage containing a cause value which indicates that a congested cellcondition exists; a monitoring of the downlink channels indicates thatthe number of connection setups being performed by the network per unittime has exceeded a threshold; and a monitoring of the downlink channelsindicates that the network is transmitting to other UEs a reject messagecontaining a cause value which indicates that a congested cell conditionexists, wherein the number of such reject messages being transmitted toother users equipment has exceeded a threshold.
 4. The method of claim2, wherein increasing the probability value for de-prioritizing thefirst cell comprises increasing the probability value within a range upto 100 percent, directly co-related to a number of consecutive failuresregistered for consecutive RACH procedures, wherein a higher probabilityvalue makes it more likely that the UE will de-prioritize the priorityvalue of the first cell.
 5. The method of claim 1, wherein assigning aselected time period comprises randomly selecting a first time periodfrom among a range of available time periods, wherein the range ofavailable time periods comprises at least a shorter time period duringwhich at least one subsequent RACH procedure can be completed by the UEand a longer time period during which multiple subsequent RACHprocedures can be completed by the UE.
 6. The method of claim 1, furthercomprising: tracking a number of failures to successfully connect to thefirst cell via the at least one first RACH procedure; and for eachconsecutive failure detected, increasing the probability value forde-prioritizing the first cell, wherein the probability value increasesfrom a baseline low probability to a high probability in N number ofincrements.
 7. The method of claim 6, further comprising: in response toexpiration of the time period following de-prioritizing of the firstcell: returning the priority value to a default priority value for thefirst cell; and resetting the probability value to a baseline lowprobability.
 8. The method of claim 1, wherein the de-prioritization ofthe first cell is only performed if at least one of a group ofconditions is detected, the group of conditions comprising: a previouslyreceived broadcast message indicates that a congested cell conditionexists; the network responds to a request by the UE for a connectionwith a reject message containing a cause value which indicates that acongested cell condition exists; a monitoring of the downlink channelsindicates that the number of connection setups being performed by thenetwork per unit time has exceeded a threshold; and a monitoring of thedownlink channels indicates that the network is transmitting to otherUEs a reject message containing a cause value which indicates that acongested cell condition exists, wherein the number of such rejectmessages being transmitted to other users equipment has exceeded athreshold.
 9. The method of claim 1, further comprising: detecting thatthe UE is in motion relative to a location at which the priority of thefirst cell could have been de-prioritized; in response to detecting thatthe UE is in motion, returning the probability value to a baseline lowprobability; and in response to detecting that the UE is in motion andthat the priority value of the first cell is currently a de-prioritizedvalue, automatically resetting the priority value of the first cell to adefault priority value.
 10. The method of claim 1, wherein reducing thepriority value assigned at the UE to the first cell for cellselection/reselection ensures that the UE does not select the first cellduring a subsequent RACH procedure when at least one suitable secondcell is also present with a default priority.
 11. The method of claim10, further comprising: attempting, by the UE, at least one subsequentRACH procedure with the at least one suitable second cell; detecting afailure to successfully connect to the at least one suitable second cellvia the at least one subsequent RACH procedure; autonomouslydetermining, based at least on a second probability value, which isgreater than 0% and less than 100%, whether to de-prioritize the atleast one suitable second cell for a second time period; and in responseto determining to de-prioritize the at least one suitable second cell,reducing a second priority value assigned at the UE to the at least onesuitable second cell for cell selection/reselection, and assigning aselected second time period during which the second priority valueremains reduced.
 12. The method of claim 1, further comprising inresponse to de-prioritizing the first cell, initiating a subsequent RACHprocedure, during a period of time before expiration of the selectedtime, to one or more selected cells, which cells are selected based inpart on the priority value of the particular cell relative to thede-prioritized value of the first cell.
 13. The method of claim 1,further comprising: determining that the failure to successfully connectduring the first RACH procedure was for initiating a first service,requested by the UE, of a plurality of different services that aresupported by the first cell, including at least one different secondservice; and de-prioritizing the first cell with respect to completionof the first service, wherein an identifier of the first cell is taggedwith the first de-prioritized priority value, which causes the UE toinitiate the at least one subsequent RACH procedure for the firstservice via a suitable second cell, while the UE issues a subsequentRACH procedure for completion of the at least one different, secondservice via the first cell, wherein each service of the plurality ofdifferent services are individually assigned the first priority value asa default assignment of the serving cell and each different service thatexperiences a de-prioritizing condition associated with that specificservice is subsequently assigned an individual de-prioritizing value fora selected time period in response to an occurrence of thede-prioritizing condition associated with that specific service.
 14. Acommunication device that is capable of establishing a connection in acongested wireless communications network environment, the communicationdevice comprising: a transceiver that is configured to attempt at leastone first Random Access Channel (RACH) procedure with a first cell thatis currently designated as a serving cell for the UE; and a RACHcontroller that is configured to detect a failure to successfullyconnect to the first cell via the at least one first RACH procedure,autonomously determine, based at least on a probability value, which isgreater than 0% and less than 100%, whether to de-prioritize the firstcell for a period of time, in response to determining to de-prioritizethe first cell, reduce a priority value assigned at the communicationdevice to the first cell for cell selection/reselection, and assign aselected time period during which the priority value remains reduced.15. The communication device of claim 14, wherein the RACH controller isconfigured to, in response to detecting that at least one failure hasoccurred during subsequent RACH procedures on the first cell, increasethe probability value for de-prioritizing the first cell.
 16. Thecommunication device of claim 15, wherein the RACH controller isconfigured to increase the probability value for de-prioritizing thefirst cell if at least one of a group of conditions is detected, thegroup of conditions comprising: a previously received broadcast messageindicates that a congested cell condition exists, the wirelesscommunications network responds to a request by the UE for a connectionwith a reject message containing a cause value which indicates that acongested cell condition exists, a monitoring of the downlink channelsindicates that the number of connection setups being performed by thewireless communications network per unit time has exceeded a threshold,and a monitoring of the downlink channels indicates that the network istransmitting to other UEs a reject message containing a cause valuewhich indicates that a congested cell condition exists, wherein thenumber of such reject messages being transmitted to other usersequipment has exceeded a threshold.
 17. The communication device ofclaim 15, wherein the RACH controller is configured to increase theprobability value for de-prioritizing the first cell by increasing theprobability value within a range up to 100 percent, directly co-relatedto a number of consecutive failures registered for consecutive RACHprocedures, wherein a higher probability value makes it more likely thatthe UE will de-prioritize the priority value of the first cell.
 18. Thecommunication device of claim 14, wherein the RACH controller isconfigured to assign a selected time period by randomly selecting afirst time period from among a range of available time periods, whereinthe range of available time periods comprises at least a shorter timeperiod during which at least one subsequent RACH procedure can becompleted by the UE and a longer time period during which multiplesubsequent RACH procedures can be completed by the UE.
 19. Thecommunication device of claim 14, wherein the RACH controller isconfigured to track a number of failures to successfully connect to thefirst cell via the at least one first RACH procedure, and for eachconsecutive failure detected, increase the probability value forde-prioritizing the first cell, wherein the probability value increasesfrom a baseline low probability to a high probability in N number ofincrements.
 20. The communication device of claim 19, wherein the RACHcontroller is configured to, in response to expiration of the timeperiod following de-prioritizing of the first cell, return the priorityvalue to a default priority value for the first cell and reset theprobability value to a baseline low probability.